1. Technical Field
The present invention relates to a method of forming an insulating layer having silicon oxynitride and an apparatus of forming the same.
2. Discussion of Related Art
Semiconductor devices typically include a gate insulating layer formed of silicon oxide. As such devices become smaller and more highly integrated, problems arise from the corresponding decrease in thickness of the silicon oxide layer. That is, with thinner silicon oxide layers being used in smaller semiconductor devices, the useful electrical characteristics of the device are more difficult to maintain. Additionally, thin gate insulating layers may undergo undesired penetration through the insulting layer and to the substrate by a high density dopant boron (B) from a p-type (p+) polysilicon electrode during an annealing process.
It is thought that the deterioration of the electrical characteristic in the device is due to dangling bonds existing at the interface between an oxide layer and a silicon layer and interfering with the electrical layer property of the oxide layer. Because of this, it is known that the layer property can be improved by oxidizing the surface of the silicon layer to form an oxide layer, and annealing at high temperature in the presence of a nitrogen gas (N2) atmosphere or an atmosphere of a mixture gas including nitrogen gas and ammonia gas. Using such high temperatures (e.g.≧1000° C.) in the semiconductor manufacturing process, however, increases the thermal budget in the formed layer.
To partially address this problem, Japanese Patent Publication No. 93-251428 (Patent No. 2793416) discloses a lamp heating type and sheet-type processing apparatus capable of rapidly heating the structure and thereby forming a silicon oxynitride layer on the oxide layer. The device and method disclosed dry-oxidizes a silicon substrate to form a silicon oxide layer, and then treating the oxide layer with an oxidation gas including nitrogen to form the silicon oxynitride layer. More specifically, the silicon substrate is loaded inside a processing room, and oxidation gas not including nitrogen (e.g. dried oxygen gas (O2)) is flowed to heat the silicon substrate to a temperature of about 1000° C. for oxidation treatment, thereby forming a silicon oxide layer. The substrate undergoes rapid heating using an infrared lamp with a temperature increase in the range of 50 to 200° C./sec. The time of maintaining the oxidation conditions, with temperature of 1000° C. and pressure of about 760 Torr, is set about 10 seconds. Thereafter, the processing room is maintained at the same temperature and vacuum-exhausted, and oxidation gas including nitrogen is flowed into the processing room to treat the silicon oxide layer, thereby changing the silicon oxide layer to the silicon oxynitride layer. Here, the oxidation gas including nitrogen is composed of at least one gas selected from the group consisting of nitrogen oxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N2O). The oxynitridation treatment is performed at a temperature of 1000° C., and at a pressure of about 760 Torr, for about 30 seconds.
Use of rapid heating, as disclosed in Japanese Patent Publication No. 93-251428, the addresses the thermal budget problem inherent with other methods. However, this method is not generally suitable to forming an insulating thin film in a highly-integrated semiconductor device, especially those using a sheet-type processing apparatus.